The present invention relates to measurements performed in wells. More specifically, the present invention relates to measurement of process variables of a fluid in a down hole location in a well.
Deep wells are one known technique for extracting fluid from the earth. Well drilling technology is an advanced art and many techniques have been developed to increase the depth of wells and also their configuration.
During the operation and drilling of deep wells, such as oil wells, it is often desirable to measure process variables of the fluid at a “down hole” location of the well. Such process variables include pressure and temperature. However, the down hole location of a deep well can be a particularly harsh environment. Pressures may surpass 15,000 psi and temperatures may reach 375 degrees Fahrenheit. Further, the distance from the surface to a deep down hole location of the well may be great, for example, over 15,000 feet. Thus, it is difficult to place measurement equipment at a deep down hole location and any such equipment must be of a sufficiently robust design to withstand the harsh environmental conditions. Further, any measurements taken at the down hole location must then be transmitted back to the surface.